XR4Ti Archived Tech Articles

    Engine and Auxillary System Sensor Guide - A guide for locating sensors for the engine and other auxillary systems on the XR4Ti. Note: this is an image heavy page with 18 images with a total size of approximately 1.02 megabytes. If some of the lower pictures on the page display an "x" in the picture placeholder, right click and select "show picture".

Post Date:    Sat, 13 Mar 2004
Subject:      none
List:         none

I put together a series of images that will help you decipher 
where the various sensors are located under the hood of an 
XR4Ti.  The pictures were taken from both my road car (as of 
March 04) which is an 87.5 XR4Ti and the engine that came out 
of my racer, an 87 XR.  These XRs don't represent the total 
collection of variations of the sensor locations (some auxillary 
systems were changed in late 88 and 89 and some early cars had
slightly different componentry and arrangements).

Sorry this page isn't more pretty, but nothing beats raw,
unadulterated information.

ECA (engine management computer) inputs: PIP - profile ignition pickup PIP Sensor (profile ignition pickup) - hall-effect sensor for communicating crankshaft/distributor position. TFI - Thick Film Ignition (or Integrated) sensor TFI - Thick Film Ignition (or Integrated) sensor, aka "ignition module". TFI and knock sensor TFI and knock sensor (located in two possible postions, the second orientation puts it on the back side of the intake manifold). knock sensor Knock sensor in intake manifold. TPS location, ISC (Idle Speed Controller) location, engine coolant temperature sensor and EGR valve TPS location (#1), ISC (Idle Speed Controller) location (#2), engine coolant temperature sensor (#3) and EGR valve (#4). This engine coolant temperature sensor is the one the ECA (computer) reads. engine coolant temperature sensor Engine coolant temperature sensor again, shown as viewed from the front, above the valve cover. TPS, throttle position sensor shown as installed TPS, throttle position sensor shown as installed on the backside of the thottle body. VAM - Vane Air Meter VAM - Vane Air Meter, located under the airbox and surrounded by the black mounting bracket. Wiring connector is visible between the two coolant lines and the outlet of the VAM has the hose going out to the left of the picture. O2, oxygen sensor O2 sensor as located in the turbo outlet casting. BAP - barometric pressure sensor (#1), starter solenoid (#2), air door solenoid (#3) BAP - barometric pressure sensor (#1), starter solenoid (#2), air door solenoid (#3). BAP sensor tells the computer about the atmospheric pressure for injecting the correct fuel mixture. The air door solenoid controls flow of vacuum to the valve that determines whether the air in the car recirculates or feeds from the outside (it controls the "thunk" when you switch between Recirc and O/S on the fan control switch, if your system is working properly.
ECA (engine management computer) outputs: BCS - boost control solenoid BCS - boost control solenoid, for the regulation of boost pressure. On the manual transmission setup, where the boost was programmed to increase from 10 psi to about 15 psi at approximately 4500 rpm (correct rpm?), this solenoid handled the pressure increase. As you can see, it is disconnected on this car. EGR - exhaust gas recirculation valve EGR - exhaust gas recirculation valve, for the reintroduction of exhaust gasses into the intake tract. It provides several functions when operational: - reduces ignition temps by adding inert gasses to the combustion chamber (reduction of NOx in exhaust gas) - effectively reduces engine displacement by using those inert gasses to take up space in the cylinder, thereby increasing fuel economy It operates when the EGR control solenoid introduces vacuum to it. EGR control solenoid The EGR control solenoid, sends a vacuum signal to the EGR valve when activated by the ECA (engine management computer).
Miscellaneous: ignition coil (#1) and spout connector (#2) The ignition coil (#1) and spout connector (#2). The spout connector, when disconnect allows the base ignition timing setting to be adjust (prevents the ECA from advancing the ignition).
Engine Auxillaries: temperature gauge sender Temperature gauge sender, as located under the intake manifold. overboost switch Overboost switch, sets off overboost buzzer in overboost condition. radiator fan switch (#1), temperature gauge sender port (#2) Radiator fan switch (#1), as installed in the lower intake manifold. Controls the radiator fan. Additionally, the port where the temperature gauge sender is located is depicted (#2). ------------------ Post Date: Sun, 14 Mar 2004 Here's a submission by Richard Curtis: schematic of engine sensor locations
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Published by Chris Anglin.